Zinc Pyromellitate Coordination Polymers with Bis(pyridylmethyl)piperazine Tethers: A Rare Binodal Network and a New Simple Self-Penetrated Topology

Hydrothermal reaction of zinc nitrate, pyromellitic acid (H₄pyro), and isomeric bis(pyridylmethyl)piperazines has afforded a pair of three-dimensional (3D) coordination polymers with intriguing 3D topologies. {[Zn₂(Hpyro)₂(H₂O)₂(H₂-3-bpmp)]·H₂O}_n [1, 3-bpmp = bis(3-pyridylmethyl)piperazine] exhibits octahedral coordination at zinc and possesses a rare 4,5-connected binodal net with (4⁴6²)(4⁴6⁶) tcs topology. {[Zn₂(Hpyro)₂(H₂-4-bpmp)]·4H₂O}_n [2, 4-bpmp = bis(4-pyridylmethyl)piperazine] has tetrahedral coordination at zinc and an unprecedented yet very simple 3,4-connected binodal (4.8²)(4.8²10³) self-penetrated topology. Pyridyl nitrogen donor disposition and coordination geometry preference play a large role in structure-direction in this system. Complexes 1 and 2 undergo blue-violet light emission on excitation with ultraviolet light.